Owens Corning

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934 (Amendment No. __)

Check the appropriate box:

☐ Preliminary Proxy Statement

☐ Confidential, for Use of the Commission Only (as Permitted by Rule 14a-6(e)(2))

☒ Definitive Proxy Statement

☐ Definitive Additional Materials

☐ Soliciting Material Pursuant to §240.14a-12

Owens Corning

(Name of Registrant as Specified in its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

☒ No fee required

☐ Fee paid previously with preliminary materials

☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

NOTICE OF ANNUAL MEETING OF

STOCKHOLDERS AND PROXY STATEMENT

Tuesday, April 14, 2026

9:00 a.m. Eastern Time

Virtual Meeting

webcast at www.virtualshareholdermeeting.com/OC2026

This Proxy Statement, the accompanying proxy card and our 2025 Annual Report will be made available on or about March 13, 2026 to stockholders of record as of February 17, 2026.

HOW TO VOTE

Stockholders have a choice of voting on the internet, by telephone, or by mail using a traditional proxy card or voting instruction card. Please refer to the proxy card or other voting instructions included with these proxy materials for information on the voting methods available to you. If you vote on the internet or by telephone, you do not need to return your proxy card.

VIRTUAL ANNUAL MEETING AND ADMISSION

We have decided to hold the 2026 Annual Meeting of Stockholders (the “Annual Meeting”) virtually because hosting a virtual Annual Meeting enables greater stockholder attendance and participation from any location, improves meeting efficiency and our ability to communicate effectively with our stockholders, provides for cost savings to Owens Corning and our stockholders, and reduces the environmental impact of our Annual Meeting. You will not be able to attend the Annual Meeting physically in person.

We are providing these proxy materials in connection with the solicitation by the Board of Directors (the “Board”) on behalf of Owens Corning, of proxies to be voted at the Annual Meeting and at any adjournment or postponement thereof. On or about March 13, 2026, these proxy materials are being distributed to stockholders. Stockholders holding shares at the close of business on the record date of February 17, 2026 will be able to attend the Annual Meeting, vote, and submit questions in advance of the meeting by visitingwww.virtualshareholdermeeting.com/OC2026. To participate in the Annual Meeting, you must have your sixteen-digit control number that is shown on your proxy card or your voting instruction form.

HELP US REDUCE PRINTING AND MAILING COSTS

If you share the same last name with other stockholders living in your household, you may receive only one copy of our Notice of Annual Meeting of Stockholders and Proxy Statement and accompanying documents. Please see the response to the question “What is ‘householding’ and how does it affect me?” in the Questions and Answers About the Annual Meeting and Voting section for more information on this stockholder program that eliminates duplicate mailings.

OWENS CORNING

One Owens Corning Parkway

Toledo, Ohio 43659

Notice of Annual Meeting of Stockholders

By order of the Board of Directors,

Gina A. Beredo

Chief Administrative Officer and General Counsel

Toledo, Ohio

March 13, 2026